The inventive concept relates to image sensors, and more particularly, to image sensors in which the difference between dark levels of light-receiving regions and of light-shielding regions is reduced.
Image sensors are devices or electronic components that transform an optical image into an electrical image signal, e.g., a charge-coupled device (CCD) and a complementary metal oxide semiconductor (CMOS) image sensor. CMOS image sensors include front side illumination (FSI) CMOS image sensors in which light is incident on a front surface of a substrate on which unit pixels are disposed, and back side illumination (BSI) CMOS image sensors in which light is incident on a back surface of a substrate.
To secure high image quality using a CMOS image sensor and to reduce degradation in image quality, a hydrogen alloy process or an ultra-violet (UV) process may be employed during the manufacture of the CMOS image sensor to fix dangling bonds and/or interface defects in the substrate. However, in the case of the BSI CMOS image sensor, the efficiency of the hydrogen alloy process or the UV process may be lowered in a light-shielding region due to a light-shielding pattern. This can increase the difference between dark levels of a light-receiving region and the light-shielding region.